The term " bark" is used most often in a nontechnical context and refers to
all tissues external to the vascular cambium (Srivastava 1964, Esau 1965). Accordingly,
the bark is an aggregation of organs and tissues that includes phloem and secondarily
thickened tissues from the secondary plant body, as well as epidermis, cortex and phloem
derived from the primary plant body (Esau 1965). The term bark was used by earlier authors
in a technical context in reference to all dead tissues exterior to a deep-seated periderm
(de Bary 1884, Büsgen and Münch 1929). Contemporary authors refer to this aggregate of
dead tissues, which consists of alternating layers of periderms and associated tissues, as
"rhytidome", a term often considered synonymous with the term "outer
bark" (Eames and MacDaniels 1947, Esau 1965). The living organs of the bark consist
of the phloem and the living tissues of the innermost periderm, the phellogen and
phelloderm. All living tissues have been collectively termed the "inner bark"
(Eames and MacDaniels 1947). Borger (1973) provided an excellent discussion of the
development and shedding of characteristic bark types. Trockenbrodt (1990) has provided an
informative survey and discussion of terminology used in the bark anatomy literature.